However, a second dose of the vaccine after three weeks significantly increased their protection, with the researchers asking for earlier boosts in this group in the UK. The UK vaccine strategy currently includes a period of 12 weeks between doses of the coronavirus vaccines; Pfizer recommends 21 days between doses.
The study analyzed the impact of the Pfizer-BioNTech vaccine on 205 participants – 54 healthy volunteers and 151 elderly patients with solid cancers, such as breast or prostate cancer, and haematological (blood) cancers, such as leukemia. The preprint study has not yet been peer reviewed or published.
The researchers looked for levels of antibodies and T cells in their blood to identify the level of immune response against the coronavirus.
Three weeks after one dose of the vaccine, an antibody response was found in 39% of solid cancer patients and only 13% of those with blood cancer. The response in healthy volunteers was 97%.
In the solid cancer patients who received a second dose three weeks after the first dose, the antibody response shot up to 95% within two weeks of the boost. Not enough booster vaccines were given to blood cancer patients to determine response in that group.
Further evidence of the need for a boost was shown by the fact that antibody levels increased only up to 43% in people with solid cancers and 8% in people with blood cancers five weeks after their first dose. It was 100% in healthy volunteers.
“Our data provides the first real-world evidence of single-dose immune efficacy of the Pfizer vaccine in immunocompromised patient populations. We show that after the first dose, most solid and haematological cancer patients remained immunologically unprotected for at least five weeks after the primary injection. But this single-dose poor efficacy can be saved with an early booster on Day 21, ”said Dr. Sheeba Irshad, a senior clinical lecturer from the School of Cancer & Pharmaceutical Sciences who led the study.
“Based on our findings, we would recommend an urgent revision of the vaccine strategy for clinically highly vulnerable groups. Until then, it is important that cancer patients adhere to all existing public health measures, such as social distance and foreclosure when visiting hospitals, even after vaccination,” Irshad added in a statement.
Stephen Evans, professor of pharmaco-epidemiology at the London School of Hygiene & Tropical Medicine, stressed that certain limitations must be taken into account.
The change in UK policy around delaying a second dose of vaccine allowed the authors to make some comparisons between those who received a second dose within 21 days and those who did not. They have not yet provided data on those who received a second dose. after a 12-week delay, ”he said in a statement to the UK’s Science Media Center.
“Nevertheless, these results suggest that the vaccines may not protect both those patients with cancer and those without cancer,” he added.
“All of these findings are consistent with our understanding of how the immune system works in cancer patients,” said Shoba Amarnath, a researcher at Newcastle University at the Newcastle University Center for Cancer. “We know that the immune system in cancer patients is compromised compared to healthy controls. Therefore, a second vaccination boost prepares the dysregulated immune system to function with the same efficiency as healthy controls.
“The data in the study supports the idea that in patients with solid cancer, a significant delay to the second dose will extend the time period in which cancer patients are at risk for SARS-CoV-2 infection.”